The Atomic Energy Council (AEC) yesterday revealed that an industrial radiography machine listed as stolen on the council's monitor roster at the beginning of last month had been found at a metal recycling factory.
A council official refused to reveal where the machine was found, but it is believed to have been in northern Taiwan.
The stolen equipment, an industrial iridium-192 radiographer, is a "kind of x-ray machine for construction welds," the victim of the theft, Shang Yang Construction (
Industrial radiographers are used for nondestructive testing (NDT), a method of inspecting materials for potential flaws by using short wavelength electromagnetic radiation to penetrate them, AEC deputy director Yang Chao-yie (楊昭義) said.
However, unlike medical x-ray machines, which are only radioactive when they are plugged in, an industrial iridium-192 radiographer is always radioactive because of its iridium core, he said.
Because the core is encased in metal, humans can be in close contact with the radiographer without health risks "so long as the compounds within are not violently shaken and disturbed," he said. He also said that the surface radiation for the radiographer is 138.5 millisievert per hour.
"We found the iridium core with the metal casing damaged and ripped off, which means that it could pose a potential health threat to humans," he said.
"We speculate that the equipment was either stolen because of its heavy weight [20kg to 30kg], which made it valuable for resale as scrap steel, or the theft was carried out by someone in the same industry," AEC Deputy Minister Yang said.
Six workers had been in close contact with the machine's radiation source, Yang said, adding that all workers were sent for medical evaluations to examine the levels of their exposure.
Yang said that in view of past instances when radioactive materials were accidentally melted down and made into new construction materials, the council had been sponsoring the installation of radioactivity detectors at the 18 recycling factories since 1995.
"The AEC takes pride in its network preventing radioactive materials from being mistakenly recycled. This incident was a good example that stray equipment was efficiently retrieved without posing a significant threat to the general public," he said.